The scary phantoms of Musaigen no Phantom World have temporarily been exchanged with adorable teddy bears as the innocent Kurumi once again takes center-stage, transforming into a mahou shoujo to save the inhabitants of this new world, thankfully not having any romantic content at all.

That does it! Anime has pushed to lust after babies! That is my new fetish because of anime's persuasive and perverse subliminal messages. Time for me to marry a male accomplice, who shares our lust fueled by anime, and begin adopting babies to raise a harem! They'll be 赤ちゃん getting fucked! They'll be 小学生(最高!!!) getting fucked! They'll be 中学生 getting fucked! They'll be 高校生 getting fucked! Eventually the will be young girls fucking us as dirty old men! Yes! The time has come for our own legal harems!

I'm pretty sure they could at least have done Aikatsu/Precure tier legservice if nothing else, but given how the show had some pretty serious ecchi in the earlier episodes, and that it's a late night anime, yes, they could, they could show whatever they please.

No, the "youth health insurance" law by no means state anything against specifically youthful looking children's sexualization compared to teenage characters.
It's completely different that what you might think it is, please don't comment on things you don't know what they are about.
For example, showing her in a very lewd underwear would not collide with any laws. Even showing her cameltoe though panties are safe.
Full frontal nudity - that could get them into trouble, but not more than full frontal nudity of your average teenager anime girl.